Wood stave conduit



April 1942. 7

c. L. MEYERS woon STAVE CONDUIT Fiied Oct. 9, 1940 2 sheet s l VENTOR. r' -Me ers TOR by April 21, 1942. v c. L. IMEYERS 2,280,339-

' woon sTAVE cqunuxw Filed 061;. 9, .1940 I 2 Sheets-Sheet 2 Cykil L ORNEY Patented Apr. 21, 1942 PATENT OFFICE 2,585,339 woon STAVE CONDUIT Cyril L. Meyers, Portland, Orega, assig nor to Forest Products Treating Division of Nebraska Bridge Supply & Lumber Company, a corporation of Nebraska Application October 9, 1940, Serial No. 360,449

4 Claims. c1. 138-79) ll/1y invention relates to conduits comprising a plurality of longitudinally disposed abutting staves arranged in a circular course and held in said course by exteriorly arrangedbands.

The principal object. of my invention is to pro- 5 vide a conduit of this character made of staves so formed that a culvert formed thereof may deform slightly from said circular course without causing said conduit to collapse.

Affurther object of my invention is to provide a conduit of this character made of staves of uniform cross section whereby the conduitcan be varied in diameter by increasing or decreasing thenumber of staves in each course.

To this end I provide individual staves for making up the conduit having marginal edges so formed that theymay accommodate themselves to a conduit from twelve inches to forty-eight inches in diameter, the edges of 'each of said staves being formed sothat they may have some limited articulation with the. edges of the adjacent staves. Each stave is provided with one edge constituting a tongue section and the other edge a groove section. The tongue section of each stave is provided with two circularly formed tongues having a common center of radius, and the opposite edge with grooves complementary thereto. A shoulder is formed intermediate the faces of said stave edges so as to define a limiting stop for articulation in one direction, and

on the edge of said stave adjacent the circularly formed tongue of lesser radius, a slight shoulder is formed to limit the articulation in the other direction.

Although my invention is useful wherevera prevent leakage along said edges and yet to perv mit some substantial articulation while withstanding considerable crushing load. A conduit formed of staves embodying my invention distributes the forces exerted upon the conduit substantially uniformly over the abutting edges of the staves, thus avoiding excessive localized pressures upon said edges which would cause them to be crushed or to yield to such a degree so as to destroy the effectiveness of the arch structure of such a conduit in supporting a load.

The details of my invention and other features thereof are hereinafter described with reference to the accompanying drawings, in which:

Fig. 1 is a perspective view of one course of a conduit made of staves embodying my invention,

such as two-by-fours.

a. portion of said course being shown broken away to disclose details of construction of said staves; r

Fig. 2 isan enlarged sectional view of said course as it appears when distorted by a heavy crushing load, which is shown diagrammatically;

Fig. 3 is an enlarged sectional view of two adjacent staves of the type illustrated in Figs. 1 and 2, one of said staves being shown in dot-anddash lines to illustrate the degree of articulation permissible; Fig. 4 is a. diagrammatic View of one of said staves illustrating that the centers of curvature of the two circularly formed tongues and the two complementarylgrooves at the opposite edge lie upon common points; i

Figs. .5 and 6 illustrate a modification of my invention similarly illustrated as in Figs. 3 and 4;

Figs. '7 and 8 show a further modification. of

staves embodying my invention similar in illus- A wood stave conduit embodying my invention comprises a plurality of longitudinally disposed staves 5, having a pair of circularly formed tongues 2 and 4 formed upon one edge thereof and complementary grooves 'I and 3 formed upon the. other edge thereof. Said staves preferably are relatively fiat and may be made of stock That is, said staves may be made of wood two inches thick and four inches wide, although they are not limited to these dimensions. The tongue 2 occupies substantially one-half of the thickness of the stave, while the groove l occupiesa greater proportion of the thickness so as to provide that degree 'of articulation shown in. Fig. 3. The circularly formed tongue 4 occupies substantially the other half of the" thickness, while the groove 3 with which it seats on an adjacent stave occupies the remainder of the thickness not occupied by groove I. Each of" said pairs of tonguesand grooves are concentric, that is, the tongues 2 and 4 are concentric about the point Ila while the. grooves I and 3 are concentric about the point] l,-as is illustrated in Fig. 4.. Thus if a section of conduit is considered supported by a base diagrammatically illustrated as 6 and is caused to support a weight diagrammatically illustrated as 1,' said conduit is permitted to become distorted from a circular course to a fiat, elliptical course as is illustrated in Fig. 2. The staves 8 and 9 and those diametrically opposite thereto are permitmally occupy when their outer faces are in abutted to articulate to the degree of play introduced by the difference in width of the groove 3 as compared to the width of the tongue 4. In this way the conduit formed of staves embodying my invention may be distorted by such a heavy external load so that the staves directly beneath 9 said superposed load may articulate to permit the conduit to become distorted from, a circular course. It may be noted that the edges of each of the individual staves comprisingsaid conduit ranged substantially at the middle of the edges I without ,subjecting the staves to rupturing strains which will fracture said staves.

remain in close contact with theQabu'tting edges of the adjacent staves, whereas if said circular tongues and grooves were not concentric they would be forced apart by said distortion.

I prefer to maintain close contact between 'It' is a diiiicult matter to provide a stop on flwoodstaves of this character which will prevent buckling, and the ability of a wood stave conduit of this character to resist crushing loads depends upon the maintenance of an arch strucsaid circular portions for two reasons. First,

there is less danger of the pipe leaking if there are large contact areas between the edges of the adjacent staves. Second, the pressure due to a load tending to crush the pipe is substantially uni-form over a large area and crushing and rotatively to a point where any portion of the conduit has reverse curvature, because if such a point is reached the conduit at that point will tend to buckle, because I do not intend tohave said staves supported interiorly. That is, re-

ferring to Fig. 2, where a section of conduit is shown supported by a block 6 having a relatively narrow surface andloaded by a weight diagrammatically indicated as "I, the pipe will be distorted so that the staves 8 and *9 will lie substantially in the same plane. point where further'distortion of the pipe will produce reverse curvature and buckling and thus further articulation must be restricted. To this end the tip portion ID, of the circularly formed groove 3 is formed into an eccentric arc of a circle, the center not being at .the point II. The outer wall of the tongue 4 is given a similar complementary curvature. Thus, further articulation of the staves 8 and 9 is resisted by the This is the 41) binding of said portions to and 12 when they constituting the conduit will not be fractured and rendered unusable later. That is, if a section of conduit should buckle, either the slight eccentric portions l2 or the tips 10 will be crushed. This, however, does not prevent said conduit from being later reassembled from said staves,

because. said staves do not fracture through their middle portions, for example. It is desirable, therefore, that said portions l0 and I2 be limited more by friction as they approach their limit of articulation and articulation is inhibited by increased friction rather than by crushing or rupturing pressures,

' When the parts are arranged as illustrated in I Fig. 2, the staves l3 and M, for example, are articulated to'a curvature shorter than they norture immediately beneath the superposed load. Thus, if the wood along the abutting joints of staves l3 and M yields even slightly, the arch structure will spread to cause the arch to collapse. It follows that the articulated joint between sta-ves I3 and 14 should have a good hearing surface, that is, the contact area should be large. Therefore, instead of providing a stop at the inside face of the joint between the abut ting edges ofstaves I3 and I4 where it would be subjected to excessive pressure, I provide a stop substantially at the middle of said joint where it serves to prevent further articulation without being over-stressed.

In Figs. 5 and 6 I illustrate a stave of slightly different section embodying my invention, the main difference being in the formation of the uppermost edge of the groove 3 and the tongue section 4. For this reason I give similar letters of reference to the other parts illustrated in Figs. 5 and 6 as in Figs. 3 and 4. At the outer edge 18 of the groove 3 I form a relatively rounded -lip and on the outer edge of the tongue 4 I provide-acomplementary groove l9 into which said lip-l3 can seat when the staves are arranged in substantial alinement as the staves 8 and 9 are arranged in Fig. 2. This provides an engagement between the parts 18 and I9 rather than a frictional over-riding as in Fig. .3.

The advantage of this structure is that a sharp 55 to collapse before rupturing strains are set up in the main body of the staves which would cause them to bebroken'and no longer usable.

In Figs. '7 and 8 I show a still further modification of my invention. In said figures, staves 2d are provided with grooves 25 and 22 upon one edge and tongues 23 and 2 on the opposite edge. As in the previous modification, said tongues and grooves are formed about common centers so as with the face 25 of an adjacent stave whenthe parts are arranged as shown in Fig. 7, and thus limiting factors are provided for articulation between adjacentstaves. In this modification the faces 28 and 21 are formed upon straight lines rather than upon curved lines as shown in Fig. 5, but their functions are substantially the same.

In Fig. 9 I illustrate how a relatively small diameter conduit can be formed of staves embodying my invention and in this view staves are illustrated as detailed inFigs. 3 and 4. When a conduit is made of said small diameter it is arranged so that the faces l5 and I6 are substantially in abutment and thus no articulation can take place to cause said staves to move inwardly so that they form sharper angles one with the other.

In Fig. 10 I illustrate a conduit of substantially larger diameter in which the staves are arranged so that the portions Ill and I2 of the abutting staves move into approximate abutment. I do not deem it practical to make a conduit of such large diameter that said portions I0 and I2 are actually in abutment, because then any deformations, such as is illustrated in Fig. 2, cannot take place without causing lips l0 and I2 to be crushed or otherwise broken, and thus I deem a conduit substantially as is illustrated in Fig. 10 to be the largest practical size to be madeof staves proportioned and arranged as illustrated.

gitudinally disposed staves arranged in a circular course with their edges arranged in abutment with .the edges of adjacent staves, said course being encircled by exteriorly arranged bands, each of said staves having a pair of circularly formed tongues formed upon one edge, and comembodying my invention, I preferably tighten the encircling bands I! so that the tongues and grooves of adjacent staves are seated tightly, one within the other. This is accomplished in the usual manner by threaded bolts lla for said bands, or by turn-buckles or the like. I preferably provide a plurality of said encircling bands for each course, as is illustrated in Fig. 1, and preferably arrange said bands so that one is arranged at each end ofa course, and thus sections can be joined end to end to produce a pipe of substantial length. 3 i

It will be understood that the word circular. as used herein, refers to portions of a circle rather than to an entire circle and that the edge with the edges of adjacent staves, said course being encircled by exteriorly arranged bands, each of said'staves having a pair of circularly formed tongues formed upon one edge, and complementary grooves formed upon the other edge,

said tongues and grooves on each of said edges,

respectively, being concentric but having radii of different lengths. 2. In a conduit comprising a plurality of lonplementary grooves formed upon the other edge,

} formed tongues formed upon one edge, and complementary grooves formed upon the other edge, said tongues and grooves on each of said edges,

, respectively, being concentric but being of a different width, respectively, and having radii of different lengths, and being separated by a face arranged intermediate said tongues and grooves, respectively, and extending laterally to join the two circularly formed elements, the tongues and grooves, respectively, of smaller radius on said stave edges terminating on an eccentric shoulder whereby deformation of said conduit maybe had within fixed limits from a circular section to a flattened elliptical section in which those staves lying adjacent the conjugate axis are arranged approximately in straight alinement without varying substantially the area of edge contact of said staves one with the adjacent one.

4. In a conduit comprising a plurality of longitudinally disposed staves arranged in a circular being encircled by exteriorly arranged bands,

each of said staves having a pair of circularly formed tongues formed upon one edge, and complementary grooves formed upon the other edge, said tongues and grooves on each of said edges, respectively, being concentric but being of a different width, respectively, and having radiiof different lengths, and being separated by a face arranged intermediate said tongues and grooves, respectively, and extending laterally to join the two circularly formed elements, the tongues and grooves,respectively, of smaller radius on said stave edges terminating in an eccentric shoulder of slight width whereby deformation of said 'conduit may be had within fixed limits from a cir-. cular sectionto a flattened elliptical section in which those staves lying adjacent the conjugate axis are arranged approximately in straight alinement without varying substantially the area of edge contact of said staves one with the adjacent one.

CYRIL L. MEYERS. 

